Electrical wiring device



5 Sheets-Sheet 1 Filed March 6, 1961 INVENTOR. HENRY J. MODREY FIG.

Feb. 18, 1964 H. J. MODREY 3,121,599

ELECTRICAL WIRING DEVICE Filed March 6, 1961 3 Sheets-$heet 2 INVENTOR.

HENRY d. MODR EY Feb. 18, 1964 H. J. MODREY 3, 9

ELECTRICAL WIRING DEVICE Filed March 6, 1961 3 Sheets-Sheet 3 INVENTOR.

HENRY J. MODREY BYMMWXM A T TOR A/E' United States Patent 3,121,599 ELECTRICAL WERTNG DEVECE Henry J. lviodrey, Stamford, Conn, assignor to Harvey Huhhell, Incorporated, Bridgeport, Conn, a corporation of Qonnecticut Filed Mar. 6, wet, Ser. No. 93,479 25 tClairns. (Ql. ass-91 The present invention relates to electrical wiring devices comprising a receiving part or receptacle and an engaging part or cap, and more particularly to electrical connectors with round cap pin contacts. It relates in particular to wiring devices made to comply with the standards established in European countries which employ round pin contacts in various configurations.

Standard connectors of the type referred to are held together by the friction between cap and receptacle contacts and disengage on pull. The contact friction decreases with continued use, with the result that connectors tend to fall apart or to disengage on too slight a pull.

In some instances, separate accessories such as screw clamps are used to hold the connector together. Connectors are known which have a positive lock, generally in the form of a threaded ring or an external latch which engages receptacle and cap. Such connectors are expensive in manufacture and time-consuming in use.

Other locking connectors operate by twisting the cap relative to the receptacle. Locking is eifected by flagshaped cap contacts engaging the receptacle. The usefulness of this type of locking connector is universally acknowledged. However, connectors of this type are not interchangeable with any wiring device system, flat prong or round pin, which has been established as a national standard in the various countries of the world. In industrial plants, standard and locking connectors are often found side by side. This lack of interchangeability tends to decrease the usefulness of locking connectors because electrical devices cannot be plugged into any receptacle but only into receptacles which correspond to the cap which they carry. The lack of interchangeability or compatibility with national standard systems is obviously a serious impediment to the spread of locking connectors.

It is the broad object of the present invention to provide a novel and improved electrical connector of the kind above referred to, the cap and receptacle of which can be positively locked to each other and the two parts of which are each fully compatible with the complementary part of a standard or conventional round pin connector, that is, a cap according to the invention can be inserted for contact engagement in a standard receptacle and similarly a receptacle according to the invention can receive a conventional cap though no locking action is effected if either of the connected parts is a standard part.

A more specific object of the invention is to provide a novel and improved electrical connector of the kind above referred to, the cap of which is double locked to the receptacle by locking the round cap pins to the receptacle contacts and also to a part of the housing of the receptacle such as the cover plate of the housing. The two locks are independent of each other which affords the advantage that upon failure of one lock the cap pins still remain locked within the receptacle in contact engagement with the contact elements thereof. Furthermore, the provision of a double lock increases the total tensile strength of the connector and the look as the receptacle housing relieves mechanical stress at the contact elements of the receptacle.

Another more specific object of the invention is to provide a novel and improved connector in which the above "ice referred to double locking action is effected by one single operation, namely by simply twisting the cap and the receptacle in reference to each other in one rotational direction, and release of both locks is effected by one single operation, namely by twisting the cap and the receptacle relative to each other in the opposite rotational direction.

Still another more specific object of the invention is to provide a novel and improved electrical connector of the kind above referred to, the receptacle of which admits the round contact pins of a cap either of the inventive kind or of the standard kind only in the correct entry position thereby effectively preventing damage to the receptacle contacts by insertion of a cap in the wrong position in reference to the receptacle.

A further more specific object of the invention is to provide a novel and improved electrical connector in which the contact elements in the receptacle have a configuration such that the contact pins of both inventive caps and standard caps are in contact engagement with the receptacle contacts in the entry position of the pins, but that only the pins of an inventive cap can be moved into the locking position in which the cap is locked to the receptacle.

It is also an object of the invention to provide receptacle contacts of a configuration such that the round pins of standard caps are automatically returned into the entry position when an attempt is made to twist a standard cap into the locking position. A more specific arrangement of this kind is to provide a configuration of the receptacle contacts such that while the round pins of a standard cap cannot be moved into the locking position, they will be held in an intermediate position with a frictional grip thereby improving the quality of the contact engagement between the receptacle contacts and the pins of a standard cap.

It is further within the concept of the invention to arrange the receptacle contacts in a manner such that they will accept in contact making engagement pins of different diameter, thus making one receptacle available also for caps with thicker pins for heavier currents.

Yet another object of the invention, allied with the preceding ones, is to provide a novel and improved multiple receptacle which may also be in the form of a continuous outlet strip and which can receive both standard caps with round pins and caps according to the invention, the latter for locking action with the receptacle.

Another specific object of the invention is to provide a novel and improved multiple receptacle 0f the type above referred to, selected receptacles of which may be readily converted from a 2-wire system to a 3-wire system and which will accept both standard caps and inventive caps.

Still another object of the invention is to provide a novel and improved multiple receptacle, the selected receptacles of which can be converted from a 2-wire system to a 3-wire system by means of an adaptor in the form of a sleeve-shaped insert removably attachable to a selected receptacle of the multiple receptacle in alignment with the pins receiving slots thereof. Such adaptors may also be fitted upon a 2-wire wall-mounted. receptacle or upon a receptacle attached to the end of a tree conductor cord such as an extension cord, to convert such receptacles for use in a 3-wire system.

It is also an object of the invention to provide electrical connectors and multiple receptacles as above referred to, the double lock feature of which and the compatibility with standard caps and receptacles, respectively, are attained without appreciably increasing the manufacturing costs as compared with corresponding standard or conventional connectors, and Without requiring :tools or special skills to effect double lock action or release thereof.

Other and funther objects, features and advantages of the invention will be pointed out hereinafter and set forth in the appended claims constituting part of the application.

In the accompanying drawing several preferred embodiments of the invention are shown by Way of illustration and not by way of limitation.

In the drawing:

FIG. 1 is a perspective exploded view, partly in section, of an electrical connector according to the invention;

P16. 2 is an enlarged perspective view of a contact element of the receptacle of the connector and of a fragmentary view of a cap pin coacting with the contact ele ment;

FIG. 3 is a perspective exploded view of a modification of the cap of the connector and of the cover plate of the receptacle;

FIGS. 4A, 4B and 4C are sectional views of modifica tions of the contact elements of the receptacle and of a cap pin coacting with the same;

FIG. 5 is a perspective exploded view, partly in section, of a modification of an electrical connector according to the invention;

FIG. 6 is a plan view upon the receptacle of the com neotor according to H6. 5;

PEG. 7 is a perspective view of a modified connector cap and a receptacle cover plate coacting with the cap;

FIG. 8 is a perspective view of a further modification of a contact element of a receptacle according to the in vention;

FIG. 9 is a plan view of FIG. 8;

FIG. 10 is a plan view, partly in section, or" another modification of a receptacle contact element;

FIG. 11 is a perspective exploded view, partly in sec tion, or" a multiple receptacle or continuous ourtlet strip according to the invention; and

FIG. 12 is a perspective view of an insert attachable to the multiple receptacle or strip of FIG. 11 for converting the same from a 2-wire system to a 3-wire system.

Referring first to FIG. 1 in detail, the electrical connector according to this figure comprises a cap 1, a receptacle 2 and a cover plate 3.

:The cap shown in FIG. 1A comprises an insulation body 4 made of two parts held together by a joining screw 5. The insulation body mounts two round contact pins 6 and 7. The two pins should be visualized as being mounted within the insulation body in a suitable and conventional manner and connected to two wires 8 and 9 led into theinsulation body. Each pin has a lower recess or groove 10 near its base and a second upper recess or groove 11 at about its middle. The grooves are shown as circumferential grooves but need not to encircle the entire pin. The depth of the grooves is shown somewhat exaggerated for clarity of illustration. The configuration of the non-grooved portions of the pins should be visualized as being the standard configuration of contact pins used for the range of current involved, that is, the recesses are formed by partly reducing the normal pin diameter rather than partly enlarging the same. The significance of that design will be pointed out hereinafter.

The receptacle of the connector is designed for mounting in a wall recess or box which is then covered by cover plate 3. The receptacle comprises an insulation body 15 in which are formed two recesses 16 and 17 in the peripheral wall of the generally cylindrical insulation body. Recesses 15 and 17 accommodate two contact elements lit and 19. Each contact element is formed oi a metal sleeve of generally fi-shaped cross section and slotted at one end to permit transverse flexing of the sleeve. The slotted end of each sleeve is extended by a tab 18a and 19a (not visible). The tabs serve to secure the contact elements to a Wall portion of the respective recess 16 or 17 by means of a rivet or screw 20 and also to receive a binding screw 2& for connecting lead-in wires 22 and 23. The slotted end of each sleeve is further formed with lock- 4 ing flags 2d which protrude somewhat inwardly into the peripheral outline defined by the respective sleeve portion as can be more clearly see in FIG. 2.

The non-slotted part 1819 and 1%, respectively, of each sleeve constitutes the entry part of the respective sleeve and the slotted part and llflc, respectively, or" each sleeve constitutes the locking part of the respective sleeve. The inner peripheral outlines of both, the entry part and the locking part of each sleeve are such that they will receive the full diameter of cap pins 6 and 7, except the portion in each locking part constricted by the respective locking flags.

The cover plate 3 for the receptacle is made of a suitable insulation material and has two arcuate slots 25 and 2m; to permit entry of the cap pins into the receptacle. Each arcuate slot has a wide or entry portion 25a and 26a, respectively, and a narrow or locking portion 25b and 26.5, respectively. Each entry portion has a peripheral outline fitting the full diameter of the non-slotted portions of the cap pins and each locking portion has a peripheral outline fitting the reduced diameter of grooved pin portions 1'0. Cover plate 3 is secured to the receptacle, after the same has been mounted in its recess by means of its cars 27, by any suitable means such as a screw 28 threaded into a screw hole 29 in the top wall of insulation body :15. To facilitate alignment of the cover slots with the contact elements of the receptacle, locating pins 38 are preferably provided which fit corresponding openings 31 in insulation body 15.

The provision of a wide or entry portion 25a and 26a in the arcuate slot is of specific importance. Without this feature, a cap could be inserted at both extremities of the slots. However, at the end opposite to the entry position, the cap pins could not penetrate beyond the locking flags 2d of the receptacle contact (see FIG. 4) and could therefore not enter to their toll depth.

Any subsequent attempt to force the cap deeper into the receptacle, would tend to damage the locking flags.

The configuration of the arcuate slots makes wrong entry impossible, saves instructions, and prevents damage to the locking mechanism. It serves to make the connector fool-proof in use.

Let it now be assumed that the receptacle and its cover plate are installed in a conventional manner and that it is desired to insert cap 1 in the receptacle.

As is evident, the configuration of slots 25 and 26 compels insertion of the cap in the correct position, that is, in the position in which the tips of cap pins 6 and 7 are aligned with entry portions 25a and 26a since the cover slots will not receive the cap pins in any other position. The cap is then pushed home so that pins 6 and 7 occupy the entry parts 18b and 19b of the sleeves. The cap pins are now in contact engagement with the receptacle contacts in the manner of a standard connector, but the cap is not locked to the receptacle. To eflect locking, the cap is twisted relative to the receptacle into a position such that both pins enter into the locking part and 190, respectively, of the sleeves. As a result, locking flags 24 engage grooves 11 and the locking portions 25b and Zeb of slots 25 and 26 extend into lower grooves 10 of the cap pins. The cap is now doubly locked to the receptacle, namely, by upper grooves 11 at the contact elements and by lower grooves 10 at the cover. Such double lock assures a high quality contact connection and also greatly strengthens the resistance to any force tending to pull the cap out of the receptacle. Furthermore, if one of the two locks should fail, .for instance, if the cover should splinter at its slots the cap is still locked to the receptacle. Similarly, if one or several locking flags should fail, for instance, by being bent out of position, the cap will remain locked at the cover plate. In a 2-pin connector, there are therefore four separate locks holding cap and receptacle together. Should three locks fail, the remaining one will still hold the connector in locked engagement. Should all four locks fail, the connector is still friction-engaged in the manner of a conventional standard connector. This multiple fail safe feature is highly desirable for industrial and especially military applications.

As has been previously pointed out, the locking grooves in the cap pins are formed by partly reducing the full peripheral outline thereof rather than by increasing the peripheral outline of the pins at any portion beyond the normal or standard peripheral outline of the pins. This affords the important advantage that both the cap and the receptacle are fully compatible with a standard component. As is evident, a standard cap, that is, a cap having round pins without any grooves can be inserted through slot portions a and 26a into the entry parts 18b and 19b of the contact elements and will make contact with the contact elements. Of course, due to the absence of grooves in the pins the cap cannot be twisted into the locking parts of the contact sleeves. Hence, no locking action can be eifected. Similarly, a cap according to FIG. 1A can be inserted into a standard receptacle in the usual manner and will make contact with the contact elements of such receptacle.

FIG. 2 shows a contact element of the kind used in the receptacle of FIG. 10 on an enlarged scale, except that an internally protruding indentation is provided at the constricted part of the sleeve, preferably at opposite sides thereof. Indentation 35, which is an optional feature, is located at the same level as the locking flags and serves as a stop preventing or at least impeding any attempt to turn a contact pin which does not have the upper groove ll from a position occupying sleeve part 185 (or 1%) into the sleeve part 18c (or 19c).

FIGS. 3A and 33 present a somewhat simplified design according to the invention. The pins of the cap have upper grooves 11c: only. The cap pins of FIG. 3 are designed to be locked to contact elements as shown in FIGS. 1C and 2. To permit twisting of the cap of FIG. 3 in the cover plate 3a, the slots 31 and 32 of that cover plate are arcuate and of a uniform width such that they will receive the full diameter of cap pins 6a and 7a and will permit twisting of the cap pins within the cover plate.

As is evident, the design of FIG. 3 provides a single locking action, but it also affords the advantage that both the cap and the receptacle, which may be of the kind shown in FIG. 'lC, are fully compatible with standard components.

The cap, either according to FIG. 1 or FIG. 3, is released by returning the same into its initial position in which the cap can be withdrawn from the receptacle.

FIGS. 4A, 4B and 4C show three modifications of the contact elements of the receptacle. In all three figures a contact sleeve, basically of the kind illustrated in FIG. 2, is shown in plan View. The sleeves are desig nated by 36, 37 and 38, respectively. Each sleeve has locking flags 36a, 37a and 38a, respectively of the kind previously described. In addition, the sleeve according to FIG. 4C is formed with internal indentations 38b in its constricted part.

FIG. 4A shows the coaction of the sleeve with a nongrooved contact pin 46 (shown in full lines) and a grooved contact pin ll (shown in dotted lines).

*l-G. 43 also shows the coaction of the sleeve with the non-grooved contact pin 4e and the grooved contact pin 41, respectively.

FIG. 4C shows the coaction of the sleeve with the grooved contact pin 41.

The internal configuration, and more particularly, the ratio of transverse width and length of the sleeve are such that non-grooved pin w shown in the entry part of the sleeve can be turned only through an angle at before being stopped by engagement with flags 36a. As is apparent, the longitudinal center axis of pin 40 has not passed the constricted portion of the sleeve when the pin is stopped. Accordingly, the tension of the spring caused by the movement of pin it} from the illustrated position into the position in which it is stopped will automatically force the non-grooved pin back into its initial position.

A grooved pin may be readily turned through an angle 3 and into the position in which it is shown. In that position the pin is locked and it is also retained in that position since its center axis has passed beyond the constricted portion of the sleeve. In other words, an inventive cap is allowed to turn to the locked position whilst a standard cap will snap back to the entry position.

The sleeve according to FIG. 4B is somewhat more elongated in reference to its transverse width than the sleeve of FIG. 4A. As a result, the non-grooved pin it? can be turned through an angle a. When pin 40 occupies the position shown in the figure in dotted lines its center axis has passed the constricted portion of the sleeve. Accordingly, the pin is in a stable position in which it is frictionally retained by engagement with the walls of the tensioned sleeve and with the locking flags. Th3 pin 49* is, of course, not locked, but its contact engagement with the sleeve is somewhat superior to that between the pin and the sleeve in FIG. 4A..

A grooved pin i l may be turned through angle 5' and is locked in the position in which it is shown. An inventive cap is allowed to turn to the locked position whilst a standard cap will frictionally jam in an intermediate position.

The sleeve design, according to FIG. 4C, does permit insertion of a non-grooved pin into the entry part of the sleeve but such pin cannot be turned within the sleeve due to the provision of stops 3%. A grooved pin 41 may be turned from the position shown in full line through an angle c into the locking position. An inventive cap is allowed to turn to the locked position whilst a standard cap cannot turn at all from the entry position.

FIGS. 5 and 6 illustrate the application of the principle of the invention to a multi-pole connector. The connector shown, by way of example, has two current-carrying pins and one thicker and longer grounding pin and conforms to the standards established in Great Britain and other countries of the British Commonwealth. it will be obvious that the invention can be applied to multi-pole connectors of different pin configurations. The connector again comprises a cap &5 (FIG. 5A), a receptacle 46 (FIG. 5C) and a cover plate 47 (FIG. 5B).

The cap comprises an insulation body 58 of suitable shape in which three contact pins 9, and are mounted. The pins should be visualized as being suitably connected to lead-in wires (not shown). Pins l9 and 52* are contact pins and pin 53. is a ground pin. The contact pins as shown have a single lower groove 2 921 and 50a, respectively and the ground pin has an upper groove Sin and a lower groove Sit: and is shown to be heavier than the contact pins. As is apparent from the previous description, pins and 5d are designed for locking with the cover plate only, whereas pin 51 is designed for double locking, that is, for locking at the cover plate and at the respective contact element of the receptacle. The connector shown is therefore a mixed type embodying both double and single locking action. it is, of course, feasible and within the scope of the invention to provide double locking at one or both con tact pins also, or single locking at the [ground pin. Furthermore, it is within the scope of the invention to omit the locking grooves at one or two of the pins of the connector according to FIG. 5. In this connection, it may be mentioned that one of the pins of FIG. 1 may have a single groove only, or no groove at all. Similarly, one of the pins of FIG. 3 may be grooveless if a locking action in one pin only is adequate.

. The receptacle of the connector of PEG. 5 comprises a generally cylindrical insulation body 52 and may be mounted in a wall recess in the usual manner by means of cars 53. The insulation body has recesses 54, 55 and to accommodate contact elements 57, 58 and 59. Each of the contact elements has a generally S-shaped cross section. Contact element 59 which is designed to receive ground pin 51, has locking fiags 6 3 and inn-er stops 61. The contact elements should be visualized as being connected in a conventional manner to leadin wires, for instance, by means of binding screws 62.

The cover plate 47 has three arcuate entry slots as, 64 and 6'5. Slots c3 and 64 are shaped to receive and lock with contact pins '49 and 5%), respectively, and slot 65 is shaped to receive pin Sit and to loc t with the groove 51a thereof.

The function of the connector is apparent from the previous description. It suffices to state that the cap is applied to the receptacle by inserting the tips of the three pins into the respective wide portions of the three cover slots, said position being the only one in which the slots will admit the cap pins. The cap is then pushed home and all three contact pins are now in frictional contact engagement with the contact elements. To lock the cap to the receptacle, the cap is twisted in reference to the receptacle into the position in which the lower grooves 4 5a, Ella and 51a lock with the cover at the respective slots and the upper groove 51b of pin 51 loclr with contact element 59, or more specifically, with the locking flags thereof. Release of the cap is effected by twisting the same in the opposite rotational direction and into its initial position in which it may be withdrawn from the receptacle.

Both the cap and the receptacle of the connector according to FIG. 5 are fully compatible with the components of standard connectors of that type. That is, the cap may be inserted into a standard receptacle and the receptacle may receive a standard cap with smooth contact pins in contact engagement. Of course, no locking action is obtainable when either one of the two components is a standard component.

FIG. 7 illustrates application of the principle of the invention to a 2-wire cap with ground connection which con-forms with German wiring device standards (SCHUKO). As shown in FIG. 7A, the cap comprises an insulation body 7% which has a generally cylindrical portion 70a. Body 7il mounts two contact pins 6 and 7 each having a lower contact groove 6a, 7a and an upper contact igroove 6b, 7b, respectively. The two contact pins should be visualized as being connected in a conventional manner to wires 71 and 72. At the outside of the cylindrical portion 76a of the insulation body, one or preferably two oppositely disposed ground contact strips 73 are provided which are preferably somewhat recessed in the insulation body. The ground contacts are suitably connected to a third wire 74. The peri-pheral wall of body portion "itla is further formed with two circumferentially elongated cut-outs 75 and 7s, preferably oppositely disposed.

The receptacle for the cap according to FIG. 7A is not shown, but it should be visualized as being similar to that of FIG. 1C.

The cover plate 7'7 for the connector of FIG. 7 is formed with a well 77a. The cylindrical inner wall of the well mounts two oppositely disposed springy ground tongues 78 and 79 engageable with ground contacts of the cap when the latter is inserted in the well. There are further shown at the inner wall of the well two oppositely disposed locating slots Gil (only one slot is visible) formed by protrusions Silo radially extending from the inner wall of the well. The base of the well includes two entry and locking slots 81 and 32 shaped as has been described in connection with slots 25 and So of cover plate 3 (FIG. 1B). The configuration of the cover plate and well corresponds precisely to the aforementioned German standard (SCHUKO) with the exception only of the arcuate slots til and 82 which in the standard cover plate are plain holes.

Application of the cap to the cover plate '77 and through it to the receptacle (see FIG. 1C) is efiected by inserting the cylindrical portion 78:! of the cap in the well. The slots 83?. and 82 in the well are so located that ground tongues 7 8 and 79 are in engagement with ground contact 73 of the cap and that the cut-outs '75 and '76 accommodate protrusions 39a in the well. The cap is then locked to the receptacle and cover 77 by twisting the cap in reference to the cover plate, the circumferential width of the cut-outs 75 and 76 permitting such twisting. The circumferential width of ground contact 73 in relation to that of tongues 78 and 79 must, of course, be such that the ground contact between the cap contacts and the cover contacts is maintained.

The cap is released by returning it into its initial position in which it may be Withdrawn.

Both, the cap of FIG. 7A and the cover plate according to FIG. 7B are compatible with standard components. In this connection, it may be mentioned that a standard cap does not have the cut-outs '75 and 7d of the cap according to the invention, but has-locating ribs instead. These ribs are received by the locating slots in the well. As is now apparent, the purpose of the cut-outs in a cap according to FIG. 7A is to permit twisting of such cap while preserving engagement of the loci ting ribs of a standard cap with the locating slots in the Well. The cap of FIG. 7A can be inserted in a standard receptacle. Of course, no locking action is available if either one of the two components is a standard component.

FIGS. 8 and 9 show still another modification of the contact element according to the invention. The contact element may be used in any receptacle according to the invention it locking action at the receptacle contact elements is required. Its purpose is to combine a heavy gauge contact for large current capacity with a lighter gauge spring tongue so as to ease turning of the cap. It will be obvious that a one-piece receptacle contact as shown in FIG. 2, could make turning difificult if the required metal gauge was to aiford little spring action.

The contact element has again a generally S-shaped configuration to define an entry part 85 and a locking part 86. In contradistinction to the previously described contact elements the locking element of FIGS. 8 and 9 comprises two parts 87 and 8%. Part 87 is formed with a looking flag 87a which may be lanced out of the material of the part and a stop 87b inwardly protruding in the constricted part of the contact element. Both parts 37 and 88 are made of springy metal, part 88 being preferably of a somewhat lighter gauge than part 37, Whose principal function is the carrying of current. The two parts are joined together. The wire is connected to a binding screw 89.

FIG. 10 shows a similar design of a heavy contact element, except that part dds of the contact element is retained in a recess 91a of the insulation body l of the receptacle. A coil spring 92 urges contact part 83a against contact part 87 secured by screw 89.

The contact elements according to FIGS. 8 through 10 afford the advantage of a high transverse elasticity. combined with high current carrying capacity. As a result, they provide a high quality contact engagement with cap pins inserted therein. Furthermore, they readily permit the use of pins of different diameters. For that purpose the two parts of the contact element are laid out so that they will receive a thin pin with adequate contact engagement and will yield to a thicker pin due to their high elasticity. The gripping of the thinner pin can further be improved by lancing out inwardly bent fingers out of the mat rial of the contact element defining the entry part 85 thereof.

This feature has special application to certain types of 2-pole receptacles used in Germany as a transitional measure to effect a degree of compatibility between the outgoing 2-wire system and the incoming 3-wire (SCHUKO) standard. These receptacles will receive both the 4 mm. pin contacts of the old caps and the 5 mm. pins of the new (SCHUKO) grounded caps. Inventive receptacle contacts as shown in FIGS. 8 through 10 lend themselves readily to receive and lock both sizes of pin contacts.

FIGS. 11 and 12 show a multiple receptacle or continuous outlet strip, the design of which makes use of the principle of the invention. The outlet strip comprises an insulation body or base 93 of any desired length in which are fitted at selected intervals contact elements 94. These contact elements may either be similar to the con-- tact elements according to the invention, such as contact elements 18 (see FIG. 2) or 59 (see FIG. 6), or they may be contact elements such as contact elements 57 and 53 (FIG. 6) depending upon whether or not locking action at the contact elements is desired. The contact elements are interconnected by means of bus bars 95 and 96.

The receptacle is connected through wires (not shown) entering through the base hole 11d and being attached to binding screws Ill on each bus bar. Only one such binding screw is visible. The third or ground wire, it used in the installation, is attached to binding screw 112.

The insulating base is fastened to a surface such as a wall or baseboard by screws 113. If the receptacle is designed as an individual multiple receptacle, both ends of the base should be visualized as closed. If several receptacles are used as a continuous outlet strip, their configuration is as shown in FIG. 11, and the bus bars of adjoining units are joined within the insulating base so that a multi-unit installation forms a continuous outlet strip which can be extended at will at both extremities, and to which current is fed from a single wiring connection as described.

Access to the contact elements is provided by arcuate slots 97, the configuration of which has been described in connection with, for instance, FIG. 1. As is apparent, each pair of contact elements constitutes a receptacle and any desired number of receptacles may be provided. The receptacles are capable of receiving a standard cap such as cap 98 or a cap according to the invention such as cap 1 described in detail in connection with FIG. 1. Both types of cap will be received in contact engagement, but, of course, only caps according to the invention can be locked.

The outlet strip as so far described is designed for a 2-wire system. It can be used with or without the protective cover 101 which is snapped upon beads formed along the side walls of base 93 or may be fastened in any other suitable manner. Cover 1011 is provided with circular openings lulu, one for each of the receptacles, and including two diametrically opposite cut-outs 1011). To facilitate locating of the cover so that the openings therein are in alignment with the receptacle slots locating dimples 102 may be provided.

The invention provides a convenient conversion of the outlet strip for use in a 3-wire system. For this purpose grounding springs 99 are provided at suitably spaced intervals. These springs may be fitted in a groove 1% formed in the top Wall of base 93. Springs 99 are con nected to ground as described before and make contact with metal cover 101. Openings 101a serve to receive a sleeve-shaped conversion insert 103. This insert has a cylindrical portion in which locating slots ltlSa are formed and which mounts preferably oppositely disposed ground tongues ltlfib. Cylindrical portion is secured to a ring collar M30. The insert may be fitted in a selected circular opening ltlla by lifting the cover and inserting the insert in the opening from below. The cover is then again placed upon the insulation strip. As can be clearly seen in FIG. 11, the insert is located in reference to the cover by triangular portions of the ground tongues which thus make contact with the cover which, in turn, is in contact engagement with grounding springs 99.

Insert 1G5 conforms to the cap configuration for the German (SCHUKO) standard which has been described in relation to the cover plate and Well shown in FIG. 73. It serves to receive a standard (SCHUKO) cap (in non-locking engagement) as well as a locking cap 104,

which is similar to the cap 74 shown in FIG. 7A and described in connection therewith. The shape of the insulation body of cap 104 is somewhat different from the insulation body of the cap shown in FIG. 7A, but the arrangement of the contact pins is the same and also the provision of cut-outs llM-a in the insulation body and the grounding strips ltldb.

As is apparent, the insert MP3 of FIGS. 11 and 12 corresponds functionally to the well 77a of FIG. 713. Accordingly, attachment of an insert 1% with the strip of FIG. 11 converts one outlet of the strip into a 3-wire receptacle. Any of the receptacles of the strip may be converted to a 3-wi re system by simply applying an insert thereto.

The conversion arrangement of FIGS. 11 and 12 can equally Well he used to convert a wall receptacle or connector body from a 2-wire system to a 3-wire system and vice versa. A connector body is simply a receptacle which is attached to the end oi a free electric cord such as the well-known extension cord. The front cover of such connector body would have the same slots as shown in FIG. 1B and the contact elements of the connector body would be arranged as shown, for instance, in FIG. 1C. To convert the 2-wire system thus provided to a 3-wire system, a conversion sleeve such as shown in FIG. 12 would have to be slipped over the front part of the connector body. The sleeve may then be visualized as being in contact with a grounded metal part engageable with the conversion sleeve. A cap such as cap 1&4 may then be applied to the connector body mounting the conversion sleeve. The connector body as such may be made out of plastic and mounting a metal. cap, which in turn is connected with a cable grip.

While the invention has been described in detail with respect to certain now preferred examples and embodiments of the invention, it will be understood by those skilled in the art after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope or" the invention, and it is intended, therefore, to cover all such changes and modifications in the appended claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. Electrical connector comprising a cap with several round contact pins, at least one of said pins having in its cylindrical wall an upper and a lower groove; and a receptacle including a housing having a. wall including arcuate access slots for the cap pins, at least one of said slots having a profile defining an entry part fitting the full peripheral outline of the grooved pin and a narrowed locking part fitting the peripheral outline of said pin at its lower groove, and a corresponding number of contact elements mounted in said housing, the one of the contact elements accessible through said profiled slot having a protrusion engaging the upper groove of the grooved pin when the latter occupies a position in which the lower groove thereof is located in said locking part whereby upon insertion of the pins in a position such that the grooved pin enters said entry part and subsequent twisting of the cap in reference to the receptacle into a position in which the grooved pin occupies the locking part of the profiled slot the cap is locked to the receptacle by the grooved pin at the contact element having the protrusion and also at the slotted wall of the housing.

2. Electrical connector comprising a cap with several round contact pins, at least one of said pins having in its cylindrical wall an upper and a lower groove; and a receptacle including a housing having a wall including arcuate access slots for the cap pins, at least one of said slots having a profile defining an entry part fitting the full peripheral outline of the recessed pin and a narrowed locking part fitting the peripheral outline of said pin at its lower groove, and a corresponding number of contact elements mounted in said housing, said contact elements having each a transverse width such that upon insertion of the pins in the slots all the pins are in contact engagement with the contact elements in any position of insertion within the slots, the one of the contact elements accessible through said profiled slot having a protrusion engaging the upper groove of the grooved pin when the latter occupies a position in which the lower groove thereof is located in said locking part whereby upon in sertion of the pins in a position such that the grooved pin enters said entry part and subsequent twisting of the cap in reference to the receptacle into a position in which the grooved pin occupies the looking part of the profiled slot the cap is locked to the receptacle by the grooved pin at the contact element having the protrusion and also at the slotted wall of the housing.

3. Electrical connector comprising a cap with several round contact pins, at least one of said pins having in its cylindrical wall an upper and a lower circumferential groove; and a receptacle including a housing having a wall including arcuate access slots for the cap pins, at least one of said slots having a profile defining an entry part fitting the full peripheral outline of the grooved pin and a narrowed locking part fitting the peripheral outline of the lower groove of said pin, and a corresponding number of contact elements mounted in said housing, said contact elements having each a transverse width such that upon insertion of the pins in the slots all the pins are in contact engagement with the contact elements in any position of insertion within the slots, the one of the contact elements accessible through said profiled slot having a protrusion engaging with the upper groove of the grooved pin when the latter occupies a position in which the lower groove thereof is located in said locking part whereby upon insertion of the pins in a position such that the grooved pin enters said entry part and subsequent twisting of the cap in reference to the receptacle into a position in which the grooved pin occupies the locking portion of the profiled slot the cap is locked to the receptacle by the grooved pin at the contact element having the protrusion and also at the slotted wall of the housing.

4. Electrical connector comprising a cap with several round contact pins, each of said pins having in its cylindrical wall a lower groove near its base and at least one of said pins having in its cylindrical wall an upper and a lower groove; and a receptacle including a housing having a wall including arcuate slots each giving access to one of the cap pins, each of said slots having a profile defining an entry part fitting the full peripheral outline of the respective pin and a narrowed locking part fitting the peripheral outline of the respective pin at its lower groove, and a corresponding number of contact elements mounted in said housing, said contact elements having each a transverse width such that upon insertion of the pins in the slots all the pins are in contact engagement with the contact elements in any position of insertion within the slots, one of the contact elements having a protrusion engaged with the upper groove of the pin having the two grooves when said pin occupies a position in which the upper groove thereof is engaged by said locking part whereby upon insertion of the pins in a position such that the pin having the two grooves enters the entry part leading to the contact element having the protrusion and subsequent twisting of the cap in reference to the receptacle into a osition in which the pin having the two grooves occupies the locking part of the respective slot the cap is locked to the receptacle by the pin having the two grooves at the contact element having the protrusion and by all the pins at the Slotted wall of the housing.

5. An electrical connector according to claim v1 wherein said housing comprises an insulation body including recesses in which said contact elements are mounted, and an insulation cover including said slots, said slots being disposed in alignment with said contact elements.

6. An electrical connector according to claim 1 wherein each of said contact elements comprises a transversely elastic metal sleeve, one part of the space within the sleeve 12 receiving said pins when the grooved pin occupies the entry part of the profiled slot and another part within the sleeve receiving the pins when said grooved pin occupies the locking part of the profiled slot.

7. An electrical connector according to claim 6 wherein said sleeve is of generally S-shaped cross section and longitudinally slotted to permit spreading of the sleeve for transverse passage of a contact pin within the sleeve from one half thereof into the other, the protrusion of the respective contact element protruding inwardly from the respective half of the sleeve to effect locking of the grooved pin in that half.

8. An electrical connector according to claim 7 wherein said protrusion is in the form of a flag inwardly bent out of the sleeve metal.

9. An electrical connector according to claim 1 wherein one of said contact elements comprises a metal sleeve of generally fi-shaped cross section longitudinally slotted at one end bight of the sleeve to impart transverse springiness to the sleeve, the slotted half of the sleeve having on its inner wall said protrusion engageable with the upper groove of the respective cap pin, said slotted half of the sleeve constituting the locking part thereof and the other half the entry part, the constricted mid part of the sleeve having on an inside Wall portion a protrusion also engageable with the upper groove of the respective cap pin, said latter protrusion permitting passage of a pin having such upper groove from the entry part of the sleeve into the locking part but blocking passage of a pin without said upper groove.

10. An electrical connector according to claim 9 wherein said generally fi-shaped sleeve is composed of two lengthwise halves complementing each other to define said generally S-shaped cross section, and wherein spring means yieldably urge said sleeve halves toward each other.

11. An electrical connector according to claim 1 wherein one of said contact elements comprises a metal sleeve of generally B-shaped cross section longitudinally slotted at one end bight of the sleeve to impart transverse springiness to the sleeve, the slotted half of the sleeve having on its inner wall said protrusion engageable with the upper groove of the respective cap pin, the slotted half of the sleeve constituting the locking part thereof and the other half the entry part, the distance between said protrusion and the constricted mid part of the sleeve being less than half the diameter of the entry part of the sleeve whereby a non-grooved round pin inserted in said entry part and twisted towards the locking part of the sleeve and into the constricted part thereof is returned into the entry part of the sleeve by the elastic transverse pressure of the sleeve.

12. An electrical connector according to claim 1 wherein one of said contact elements comprises a metal sleeve of generally 8-shaped cross section longitudinally slotted at one end bight of the sleeve to impart transverse springiness to the sleeve, the slotted half of the sleeve having on its inner wall said protrusion engageable with the upper groove of the respective cap pin, the slotted half of the sleeve constituting the locking part thereof and the other half the entry part, the distance between said protrusion and the constricted mid part of the sleeve being more than half and less than the whole diameter of the entry part of the sleeve whereby a non-grooved round pin inserted in said entry part and twisted toward said protrusion is frictionally retained partly in the lock ing part and partly in the mid part of the sleeve.

13. An electrical connector according to claim 1 wherein said cap comprises an insulation body mounting said round pins, and said receptacle comprises an insulation body mounting said contact elements, and an insulation cover including a well portion for receiving said cap body, said access slots for the cap pins being formed in the bottom of said well portion, and wherein said cap body at a side wall and said well portion of the cover at an inner side wall each mount a ground contact, said ground contacts being in contact engagement in any posi tion of twist of the cap in the receptacle, said cap body further having in said side wall of cutout for accommodating locating means at the inner side wall of the well portion when the cap is twisted within the well portion.

l4. An electrical connector comprising a cap with several round contact pins, at least one of said pins having a groove in its cylindrical wall; and a receptacle including a corresponding number of contact elements mounted in said housing for insertion of the pins into the contact elements, each of said contact elements comprising a transversely elastic metal sleeve, one part of the space Within the sleeve configured to receive the full peripheral outline of the pins upon insertion of the pins into the said one part and arranged to be in contact engagement with said pins regardless of the degree of insertion thereby constituting an entry part for insertion of the pins therein and another part within the sleeve constituting a locking part into which said pins are arranged to be moved by relative twisting of the cap and receptacle, the inner peripheral configuration of the sleeve being such that the pins in any position within the sleeves are substantially surrounded thereby and in contact engagement with a wall thereof, at least one of the contact sleeves having in its locking part an inwardly extending protrusion engageable with the groove in the grooved pin upon movement of said pin from the entry part into the looking part of said sleeve whereby upon insertion of the pins in the entry part of the contact elements and subsequent twisting of the cap in reference to the receptacle into a position in which the groove of the grooved pin is engaged by said protrusion the cap is locked into the receptacle by the grooved pin at the contact element having said protrusion.

15. An electrical connector according to claim 14 wherein each of said sleeves is of generally d-shaped cross section and longitudinally slotted along one of the halves thereof to permit spreading of the sleeve for transverse passage of an inserted pin, the protrusion of the respective contact element protruding inwardly from the slotted half of the sleeve for engagement with the groove of the respective pin to efiect locking of the grooved pin in said half of the sleeve.

16. An electrical connector according to claim 14 wherein one of said contact elements comprises a metal sleeve of generally ti-shaped cross section longitudinally slotted at one end bight of the sleeve to impart transverse elasticity to the sleeve, the slotted half of the sleeve having on its inner wall said protrusion engageable with the groove of the respective cap pin, the slotted half of the sleeve constituting the locking part thereof and the other half the entry part, the constricted mid part of the sleeve having on an inside wall portion defining said constricted sleeve part a protrusion also engageable with the groove of the respective cap pin, said latter protrusion permitting passage of a pin having such groove from the entry part of the sleeve into the locking part thereof but blocking passage of a non-grooved pin.

17. An electrical connector according to claim 16 wherein each of said generally S-shaped sleeves is composed of two lengthwise halves complementing each other to define said substantially e-shaped cross section, and wherein spring means yieldably urge said sleeve halves toward each other.

18. An electrical connector according to claim 14 wherein one of said contact elements comprises a metal sleeve of generally shaped cross section longitudinally slotted at one end bight of the sleeve to impart transverse elasticity to the sleeve, the slotted half of the sleeve having on its inner wall said protrusion engageable with the groove of the respective cap pin, the slotted half of the sleeve constituting the locking part thereof and the other half the entry part, the distance between said protrusion and the constricted mid part of the sleeve being less than half the diameter of the entry part of the sleeve whereby Us a non-grooved round pin inserted in said entry part and twisted towards the locking part of the sleeve and into the constricted part thereof is returned into the entry part by the elastic transverse pressure of the sleeve.

19. An electrical connector according to claim 14 wherein one of said contact elements comprises a metal sleeve of generally S-shaped cross section longitudinally slotted at one end bight of the sleeve to impart transverse elasticity to the sleeve, the slotted half of the sleeve having on its inner wall said protrusion engageable with the groove of the respective cap pin, the slotted half of the sleeve constituting the locking part thereof and the other half the entry part, the distance between said protrusion and the constricted mid part of the sleeve being more than half and less than the whole diameter of the entry part of the sleeve whereby a non-grooved round pin inserted into said entry part and twisted toward the locking part is frictionally retained partly in the locking part and partly in the mid part of the sleeve.

20. A receptacle for an electrical connector comprising an insulation body including recesses, several contact elements mounted within said recesses, each of said contact elements including a metal sleeve of generally 8 shaped cross section, one 8-part of said sleeve constituting an entry part for round contact pins of a connector cap and the other a locking part, at least one of said contact elements having a protrusion extending from the inner wall of the locking part thereof, and an insulation cover plate for said insulation body including arcuate access slots each in alignment with one of said contact sleeves, the slot correlated with the contact element having said protrusion being profiled to define a wide entry part aligned with the entry part of said contact eiement and a narrow locking part aligned with the locking part of said contact element.

21. A multiple receptacle outlet strip for an electric 2-wire wiring device, said outlet strip comprising an elongated insulation body, a plurality of contact elements mounted within said insulation body, said contact elements being arranged in longitudinally spaced pairs, each of said pairs constituting the contact elements of one Z-Wire receptacle adapted to receive the contact pins of a roun pin connector cap, selected ones of said contact elements comprising a transversely elastic metal sleeve of generally d-shaped cross section, one lengthwise half of each of said sleeves constituting an entry part and the other half a locking part of the sleeve, at least one of said contact sleeves having a locking part formed with an inwardly extending protrusion, and conductors supported by said insulation body connecting said pairs of contact elements in parailel, said insulation body being formed with arcuatc access slots, one for each contact eieinent, to provide access to said contact elements for the insertion of round cap pins, each of said slots being profiled to define a wide entry part and a narrow locking part, the entry parts of the slots and of the contact elements being in alignment and the locking parts of the slots and of the contact elements being also in alignn cut.

22. A connector cap for insertion in a selected receptacle of the multiple receptacle outlet strip according to claim 21, said cap comprising an insulation body and several round contact pins supported by said body, at least one of said pins having a groove in its cylindrical Wall, said cap being insertable in any selected receptacle for contact engagement therewith and turnable in the receptacle including the contact element having the protrusion for locking the cap to said receptacle by engagement of said groove with said protrusion.

23. A connector cap for insertion in a selected receptacle of the multiple receptacle outlet strip according to claim 21, said cap comprising an insulation body and several round contact pins supported by said body, at least one of said pins having in its cylindrical wall two longitudinally spaced grooves, said cap being insertable in any selected receptacle for contact engagement therelit with and turnable in the receptacle including the contact element having the protrusion for locking the cap to said receptacle by engagement of one groove with said protrusion and the other groove With the locking part of the respective slot.

24. A multiple receptacle outlet strip according to claim 21 and comprising a metal cover covering the side of the insulation body including said slots, said cover having openings uncovering the access slots of each of said receptacles and an adaptor for converting a Z-Wire receptacle of the multiple receptacle outlet strip to a 3-wire receptacle, said adaptor comprising a metal sleeve attachable to said cover in alignment with the access slots of a selected receptacle, said sleeve being adapted to receive a connector cap having a ground contact strip at a Wall portion engaging the adaptor sleeve when the cap is applied to the selected receptacle.

l 5 25. An adaptor for converting a Z-Wire receptacle of an electrical connector into a 3-Wire receptacle, said adaptor comprising a metal sleeve fittable upon the body of the receptacle in alignment with the access slots for the contact elements of the receptacle.

References Cited in the file of this patent UNITED STATES P TENTS 2,127,473 Sacco Aug. 16, 19*38 2,703,871 Woodhead Mar. 8, 1955 2,781,498 Maly Feb. 12, l957 2,886,793 Katzrnan May 12, 1959 FOREIGN PATENTS 1,025,480 Germany Mar. 6, 1958 

1. ELECTRICAL CONNECTOR COMPRISING A CAP WITH SEVERAL ROUND CONTACT PINS, AT LEAST ONE OF SAID PINS HAVING IN ITS CYLINDRICAL WALL AN UPPER AND A LOWER GROOVE; AND A RECEPTACLE INCLUDING A HOUSING HAVING A WALL INCLUDING ARCUATE ACCESS SLOTS FOR THE CAP PINS, AT LEAST ONE OF SAID SLOTS HAVING A PROFILE DEFINING AN ENTRY PART FITTING THE FULL PERIPHERAL OUTLINE OF THE GROOVED PIN AND A NARROWED LOCKING PART FITTING THE PERIPHERAL OUTLINE OF SAID PIN AT ITS LOWER GROOVE, AND A CORRESPONDING NUMBER OF CONTACT ELEMENTS MOUNTED IN SAID HOUSING, THE ONE OF THE CONTACT ELEMENTS ACCESSIBLE THROUGH SAID PROFILED SLOT HAVING A PROTRUSION ENGAGING THE UPPER GROOVE OF THE GROOVED PIN WHEN THE LATTER OCCUPIES A POSITION IN WHICH THE LOWER GROOVE THEREOF IS LOCATED IN SAID LOCKING PART WHEREBY UPON INSERTION OF THE PINS IN A POSITION SUCH THAT THE GROOVED PIN ENTERS SAID ENTRY PART AND SUBSEQUENT TWISTING OF THE CAP IN REFERENCE TO THE RECEPTACLE INTO A POSITION IN WHICH THE GROOVED PIN OCCUPIES THE LOCKING PART OF THE PROFILED SLOT THE CAP IS LOCKED TO THE RECEPTACLE BY THE GROOVED PIN AT THE CONTACT ELEMENT HAVING THE PROTRUSION AND ALSO AT THE SLOTTED WALL OF THE HOUSING. 